As for an audio device to be connected to a host apparatus such as a personal computer by USB, when the audio device is connected to the host, the audio device receives a volume value being held by the host and sets it in a volume control circuit. If the volume value that is received from the host and set in the volume control circuit is larger than a volume value that has been set therein so far, a loud sound may be output immediately after the connection to damage the device or adversely affect a human body. If the volume value received from the host is disregarded to solve this problem, equalization to the volume setting value of the host is not made.